Tuning a musical instrument with vibrato system: A mathematical framework to study mechanics and acoustics and to calculate optimal tuning strategies.

String instruments such as electric guitars are often equipped with a vibrato system, which allows varying the pitch of all strings as a musical effect. It is usually based on a mobile bridge that is kept in balance by the strings and a coiled spring. Tuning such an instrument is complex, since adjusting the tension on one string will alter all other strings' tensions. In practice, a heuristic method is used where all strings are repeatedly tuned to the desired pitch, which appears to reliably yield correct pitches after a while. It is unclear why this method works; an analysis is lacking. This paper presents a mathematical model to study this subject in detail; the model captures the underlying mechanics and acoustics and can be used to simulate a typical tuning process. The paper then verifies the model with experimental data and shows that the model permits calculation of optimal tuning strategies that use the least number of adjustment steps.

JAK/STAT-dependent gene regulation by cytokines.

The Janus kinase-signal transducer and activator of transcription (Jak-STAT) pathway is essential for the signal transduction of many cytokines. Dysregulation of Jak-STAT signaling is associated with various human diseases. Recent studies have helped to shed some light on regulatory mechanisms that modify quantity and quality of the signaling response. Here, we summarize our current knowledge on Jak-STAT signaling.

Structural changes in calcium-binding allergens: use of circular dichroism to study binding characteristics.

BACKGROUND: Several studies showed that calcium-binding proteins have a fixed place in the spectrum of allergenic substances. Often the binding of a calcium ion induces conformational changes and affects immunoglobulin E-binding to the allergen. Hence, the quantitative characterization of the binding to calcium is of importance to understand both the biologic and allergenic activity of these proteins. AIMS OF THE STUDY: In the present study we describe a procedure for determining the stoichiometry and dissociation constant (K(D)) of calcium-binding allergens using circular dichroism (CD) techniques. For the experiments, we used recombinant Bet v 4, a two EF-hand allergen from birch pollen. METHODS: Solutions of Bet v 4 were titrated with calcium and the change in molar ellipticity at 222 nm was monitored with a CD spectropolarimeter. RESULTS: The determination of the binding stoichiometry as well as of the K(D) for one EF-hand (4 microM) demonstrated the applicability of the method. CONCLUSIONS: CD-monitored calcium-titration of protein solutions represents a fast and easy method for determining the binding characteristics of calcium-binding allergens.